When utilizing proportional hydraulic solenoid valves, especially when utilizing them in the environment of control of an automatic transmission, it is desirable that a spring rate of the compression spring, which positionally biases an armature of a control valve, be matched with the “spring rate” of the solenoid magnetic force such that the combination of the two spring rates cancel one another resulting in a uniform net force across a stroke range of a solenoid valve. The cancelling out of the spring rates provides a hydraulic solenoid valve design that regulates a control pressure independent of a supply pressure and temperature. The freedom of utilizing a solenoid valve as described above, in most applications is denied due to the manufacturing tolerances of the spring and the solenoid magnetic components. Matching of the spring rates is not precise enough to achieve the desired performance. It is desirable to provide an apparatus and a method supplying an ability to calibrate the rate of the compression spring.
Prior to the present invention, a compression spring load was often calibrated by pressing or screwing an adjustment component into another solenoid component to achieve a load upon the armature of the solenoid at a specific height. However, the adjustment components that adjusted the spring provided no means to adjust the rate of the compression spring. It is desirable to provide an apparatus and method of utilization thereof of adjusting the spring rate of a compression spring utilized in a proportional hydraulic control valve.